[ Castiel doesn't want to face it - any of it - because confronting it makes it all that much more real. He knows how unstable he is, how dangerous, and while at the moment he's not bringing any Leviathan down on their heads, how long is it going to be before he endangers Dean one way or another. Retreating back into his poor, damaged mind was better, in some ways.

And yes, he was trying to ditch Dean. Sort of. He was trying to throw him to those people - his people, who actually liked him - and make a break for it, because Dean would be better off surrounded by human beings. But at the same time it's not even remotely what he wants to do: he's just afraid, afraid for himself, afraid for Dean, but mostly afraid for a world with him in it. ]

If we try to fix this world too, [ He said, shakily, ] What's to stop us making things even worse than they already are? I break-- [ He grimaces. ] --I break everything I touch, Dean. Everything.